Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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An injector for preventing accidental needle sticks
Field of the invention
The present invention relates to injector for preventing accidental needle
sticks. The injector comprises a needle guard, which needle guard when
activated
safeguards the needle by preventing access of a user to the hypodermic needle
and mechanically locking the needle guard to the barrel of the injection
device.
The needle guard has dual function design where it functions firstly as
extended
plunger in cooperation with the needle cap to perform the injection and
secondly
as a needle guard safeguarding the needle and protecting the surroundings
against needle stick injuries. The dual function steps are performed with the
same hand wise configuration and hence without any change of finger grip or
handling between the steps.
Prior art
The problem of protection against needle stick injuries is well recognised
but a sufficient solution has not been provided. Thus, there exists a variety
of
solutions and products that aim to solve the serious problem where hospital
staff,
especially doctors and nurses are often exposed to and suffer sharp injuries
with
used needles and syringes, which in many cases lead to the transfer of
contagious and even deadly diseases.
The needle stick injuries most often occur because the user after a
completed injection tries to secure the needle by way of the traditional
needle
cap which is detached before the injection, which procedure leads needle stick
injuries by infected needles.
In addition, needle stick injuries can occur as a result of other situations,
but regardless of the reason, the importance of reducing these injuries is
crucial
since on a daily basis people die due to needle stick injuries since having
been
infected with deadly diseases such as HIV and Hepatitis.
One of the key barriers to implementation and use of needle stick
preventions, is that these often cost more than the customer is willing to pay
or
do not offer the ease of use required by the user. The high price of needle
stick
preventions is due to the fact that these are generally significantly more
expensive to produce due to the extra components, raw materials and workflows
which means significantly higher production price and thus also asking price.
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Besides the price which is the first prerequisite for a successful product
implementation particularly user friendliness is of the utmost importance
since
injections which are given in millions on a daily basis worldwide are
characterised
by habit and conservatism, making the user likely to reject new solutions
which
often influence user friendliness negatively compared to the usual injection
devices which have been used for decades.
Most needle stick preventions act as accessories which are usually
attached to the standard needles which are mounted on disposable syringes, but
these needle stick preventions require an additional workflow by the user
after
the injection, since the safeguarding of the needle must be made by manual
positioning of the needle stick prevention over the needle tip, which is also
connected with a relatively high risk of a needle stick injury, since this
manoeuvre is difficult to implement with the injecting hand alone, and often
requires the help of the non-injecting hand, which often results in needle
stick
injuries. With regard to user friendliness and not least safety it is
notoriously
essential that the needle be safeguarded by the injecting hand, since a large
number of needle stick injuries occur when users must use their other hand to
secure the needle or are uncertain of how to handle the actual product. For
the
same reason the World Health Organization (WHO) has prohibited other than the
use of the injecting hand like recapping is forbidden as well (attaching the
needle
cap after injection).
There also exists disposable syringes which are designed with an
integrated needle stick prevention but these solutions are often complicated
both
in terms of a large number of additional components and significantly
increased
production costs while at the same time significantly reducing safety and ease
of
use and especially the price is prohibitive for implementation of those in
large
volumes, since the components among other things, increase the physical size
of
the syringe significantly.
The latter type syringes are typically provided with a protective piece for
enclosing of the needle, but there are also syringes which retract the needle
into
the barrel by the end of the injection. However, it is very important to point
out
that the latter type syringes can function appropriately only if the user
conducts
the injection according to instructions and thus leads the plunger to the
bottom of
the barrel which is a necessity to activate the mechanism that secures the
needle
in the barrel. Otherwise, the syringe can be used a large number of times if
the
user has a demand and deliberately keeps the piston a few millimetres from the
bottom of the cylinder during injection.
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It is the purpose of the present invention to solve the problems previously
unsolved, and in particular to introduce a needle guard which is affordable,
user
friendly and integrated in a syringe. The invention is mainly dedicated to
prefilled
syringes although it can be utilised for other medical applications and
purposes.
Disclosure of the invention
The present invention relates to an injector for preventing accidental
needle sticks comprising
-a cylinder extending along a longitudinal axis, an inner wall and an outer
wall, the cylinder having an outlet at an outlet end opposite an actuating end
and
a finger grip on the outer wall, which finger grip is positioned between the
outlet
end and the actuating end,
-a piston having a piston body and a deformable sealing element, which
deformable sealing element abuts the inner wall of the cylinder at an abutting
interface and seals an annular gap between the piston body and the inner wall
of
the cylinder when the piston is inserted in the cylinder,
-a needle guard for mounting on the outside of the cylinder from the
outlet end or the actuating end, which needle guard comprises a barrel with a
mounting end opposite an operating end, the barrel having a slot for receiving
the finger grip of the cylinder when the needle guard is mounted on the
cylinder,
which slot extends from the mounting end towards the operating end,
wherein when the needle guard is mounted on the cylinder from the
actuating end in a protective position, the barrel extends along the
longitudinal
axis and projects beyond the outlet end of the cylinder so that when a
hypodermic needle is attached at the outlet end, the barrel protects a user
from
accidental needle sticks.
The invention thus presents modifications of the existing components in
addition to a new component in the form of a needle guard, which in
combination
are able to achieve a unique technical solution and solve the serious problem
of
reducing needle stick injuries. No previously suggested device is capable of
safeguarding the needle tip by continuation of the empty sequence with
unchanged finger grip which meets the WHO's desire to ensure early activation
reuse at the same time. According to the present invention the needle guard
comprises a single additional component and has a unique design, for
integration
in an injection device.
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The injector may be any kind of injector employed to deliver a
pharmaceutical composition to a subject through the skin of the subject. For
example, the injector may be a syringe, which is fitted with a hypodermic
needle
to inject a pharmaceutical composition, e.g. via subcutaneous (SC),
intramuscular (IM), intra-dermal (ID), or intravenous (IV) delivery or another
type of delivery.
The injector comprises a cylinder. In the context of the invention a
"cylinder" is any kind of tube or the like allowing the piston to be moved
from
one position in the cylinder to another. The cylinder has an "actuating end"
and
"outlet end" opposite each other. The actuating end of the cylinder allows
access
to the piston for moving it, i.e. "actuating" the piston, in the cylinder.
Likewise,
the piston may have an actuating surface facing the actuating end of the
cylinder
and an outlet surface opposite the actuating surface thus facing the outlet
end of
the cylinder. In general, the distance from the actuating end of the cylinder
to
the outlet end of the cylinder minus the dimension of the piston parallel with
the
longitudinal axis of the cylinder defines an "operating length" of the
cylinder. The
piston may be moved towards the outlet end using any means from the actuating
end, for example the piston may be moved towards the outlet end using a piston
rod or a plunger. It is preferred that the piston cannot be moved towards the
actuating end, e.g. from the outlet end, with engagement of the piston, e.g.
with
a piston rod or the like, from the actuating end.
The cylinder comprises a finger grip positioned between the outlet end and
the actuating end. The finger grip may have any form desired, which allows the
user to rest one or more fingers, e.g. two finger, while using a further
finger to
push the needle guard. For example, the finger grip may contain two protrusion
or the like on the outer wall of the cylinder. In another embodiment the
cylinder
has a single finger grip which is fitted with a ring or the like surrounding
the
cylinder thereby allowing the user to rest two fingers on the ring.
The cylinder can be considered to define a guarding length from the finger
grip to the tip of a hypodermic needle, when the hypodermic needle is attached
to the cylinder at the outlet end, wherein the longitudinal dimension of the
slot
for receiving the finger grip is equal to or larger than the guarding length,
and
the length of the barrel is equal to or larger than a total length of the
cylinder
from the actuating end of the cylinder to the tip of a hypodermic needle, when
the hypodermic needle is attached to the cylinder at the outlet end. The slot
for
receiving the finger grip of the cylinder may have any shape desirable, for
example it may be straight or curved, e.g. having a helical shape. The
cylinder
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may be made from any relevant material, and typical materials comprise
polymeric materials, such as cyclic olefin copolymer (COC), e.g. TOPAS
polymers
(supplied by TOPAS Advanced Polymers GmbH), cyclo olefin polymer (COP), or
polystyrene, or glasses. COC polymers are preferred due to their excellent
barrier
5 characteristics and thus accommodate the need for long-term storage
of
pharmaceutical agents. It is also contemplated that the cylinder may be made
from a metal or it may comprise any combination of polymeric materials,
glasses
or metals. The cross-sectional shape of the cylinder is not limited although
it is
preferred that the cylinder has a round cross-section. It is also contemplated
that
the cross-section may be oval, elliptical, polygonal, etc. When the cylinder
has a
round cross-section the diameter, e.g. the inner diameter, may have any value
conventionally used with syringes. For example, in a preferred embodiment the
cylinder has an inner diameter in the range of about 2 mm to about 10 mm, such
as 4.65 mm, 6.35 mm or 8.80 mm.
The cylinder at the actuating may be open across the whole cross-section
of the cylinder, which allows removal and insertion of the piston and thereby
also
filling of the injector via the actuating end. The cylinder may also have at
the
actuating end a ridge or protrusion(s) or the like preventing removal of the
piston
once inserted in the cylinder. In particular, the ridge or protrusion(s) may
provide
a "lock device" of a "spring-lock device" where the complementary "spring
device" is contained on a piston rod. A spring-lock device or the like can
lock the
piston rod after moving the piston to the outlet end of the cylinder thereby
preventing refilling of the cylinder.
The injector comprises a piston, which seals the contents of the cylinder
from the surroundings. The piston has a piston body and a deformable sealing
element, which deformable sealing element abuts the inner wall of the cylinder
at
an abutting interface and seals an annular gap between the piston and the
inner
wall of the cylinder. The term "abutting interface" refers to any section
where the
inner wall and the deformable sealing elements contact each other and the
"abutting interface" does not impose any limitations on either the inner wall
of
the cylinder or the surface of the sealing element. The piston will thus
define an
outlet section of the cylinder, i.e. at the outlet surface of the piston, of
the piston,
and an actuation section of the cylinder, i.e. at the actuating surface of the
piston, and prevent fluid communication from the outlet section to the
actuation
section, or vice versa, past the piston. Movement of the piston in the
cylinder
towards the outlet end will thereby eject fluid present in the outlet section
e.g.
via an outlet. The piston body does not abut the inner wall of the cylinder,
and
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only sealing elements present on the piston body abut the inner wall of the
cylinder. The piston may have one or more deformable sealing elements.
The injector has a needle guard comprising a barrel. The barrel has a slot
for receiving the finger grip of the cylinder; the slot extends from the
mounting
end towards the operating end so that the needle guard can be mounted on the
cylinder from the outlet end or the actuating end. When the needle guard is
mounted from the outlet end, i.e. with the finger grip in the slot for
receiving the
finger grip, the barrel shields the user of the injector from a needle
attached to
the outlet of cylinder before the injector is used. This position is generally
referred to as a storage position. When the needle guard is mounted on the
cylinder from the actuating end with the finger grip in the slot for receiving
the
finger grip the needle guard has a protective position after injection of a
patient
where the barrel extends along the longitudinal axis and projects beyond the
outlet end of the cylinder so that when a hypodermic needle is attached at the
outlet end, the barrel protects a user from accidental needle sticks. In an
embodiment of the invention a hypodermic needle is attached, e.g. permanently
attached, to the outlet of the cylinder.
The needle guard achieves the safeguarding of the needle simply by
continuation of the injection action and hence without any change of finger
grip
or hand configuration. This effect is achieved by introducing the slots in the
barrel
which allow for the passage of the barrel of the finger grip which according
to the
invention and in contrast to usual syringe barrels is positioned further down
the
cylinder and away from the actuating end of the cylinder.
The injector for preventing accidental needle sticks of the invention thus
has a storage position where the needle guard is mounted from the outlet end.
In
this position the needle guard will protect the user from contact with the
hypodermic needle when handling the injector prior to injecting the contents
of
the cylinder into a patient (see e.g. Figure 6 and Figure 13). The injector is
prepared for injecting the contents of the cylinder into a patient by removing
the
needle guard from its storage position and mounting the needle guard on the
cylinder from the actuating end (see e.g. Figure 7 and Figure 14). The
contents
of the cylinder are administered to the patient by pushing the needle guard,
with
a device for actuating the piston provided in the needle guard or with an
external
plunger or the like, towards the outlet end of the cylinder; when the piston
has
reached the outlet end (see e.g. Figure 8 and Figure 15), and the needle guard
is
in a "post injection position", the hypodermic needle is withdrawn from the
patient, and the pushing movement, e.g. of the user's thumb, is continued to
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move the needle guard to its protective position (see e.g. Figure 9 and Figure
16)
where the user is prevented from touching the hypodermic needle so that he is
protected from accidental needle sticks. In any embodiment of the invention
the
needle guard may be longer than the total length of the cylinder including a
hypodermic needle attached to the cylinder (as illustrated in Figure 4 and
Figure
5), which affords an additional level of protection for the user. Likewise, in
any
embodiment of the invention the needle guard may have the same length of the
total length of the cylinder including a hypodermic needle attached to the
cylinder
(as illustrated in Figure 9). This embodiment is considered to afford
sufficient
protection to the user.
The needle guard is preferably a single component, e.g. manufactured by
injection moulding from a thermoplastic material although it can be made from
glass or other material relevant for the purpose. Through its design the
needle
guard, in preferred embodiments where the needle guard is provided with a
device for actuating the piston, achieves a dual functionality firstly as
extended
plunger in cooperation with the needle cap and secondly as needle guard for
safeguarding of the needle. The injector may also have a separate plunger,
which
can engage the piston allowing the user to fill the injector before using the
needle
guard when injecting the contents of the injector into the patient so that the
user
is protected after the injection.
For reduced production costs utmost diligence has been present in order
to design the needle guard for achieving the simplest moulding cycle and as
such
the needle guard according to the invention can be moulded in a standard mould
despite the presence of protrusions and slots and at a significantly low cycle
time
per moulding sequence.
In an embodiment the needle guard is provided with a device for actuating
the piston, which can move the piston from the actuating end towards the
outlet
end of the cylinder when the needle guard is mounted on the cylinder from the
actuating end. The device for actuating the piston may be a rod, e.g. a
plunger.
When the needle guard comprises a device for actuating the piston the design
of
the needle guard enables the user to protect himself, in a simple manner,
against
undesired contact with the needle tip simply by continuing the emptying
movement by use of one and same hand and unchanged finger grip until the
barrel encloses the needle in which position the barrel may be locked.
Furthermore, when the barrel of the injector is locked after emptying reuse of
the
injector is prevented, e.g. regardless whether the user chooses to use the
needle
cap to secure the needle or not.
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The device for actuating the piston may be selected freely. In a specific
embodiment the device for actuating the piston is a compression spring
arranged
at the operating end of the needle guard. The compression spring may for
example be a helical compression spring. In an embodiment the compression
spring has a compression constant, k, in the range of 0.01 Nimm to 1 Nimm,
e.g. 0.05 N/mm to 0.5 N/m, as determined from the relation: k = F/X, where F
is
the force applied and X is the displacement of the compression spring. The
spring
may have a length in an uncompressed state in the range of 5 mm to 100 mm,
e.g. 20 mm to 50 mm, but the length in the uncompressed state, and also the
minimal length in the compressed state, will be chosen relative to the size of
the
injector. The compression spring may be an internal compression spring, which
is
compressed against the top surface of the piston by manual actuation of needle
guard via a push plate and at a given application of force causes the piston
to
move towards the bottom of the cylinder whereby injection is executed. The
force
of the compression spring is calculated from the number of turns, spring wire
diameter and the length and the result is dedicated the desire to transfer the
force to the piston by compression of the spring so that the piston, when the
given force is obtained, moves towards the cylinder outlet for execution of
injection. In this embodiment it is preferred that a hypodermic needle is
attached
to the outlet of the cylinder. It is further preferred in this embodiment that
the
injector is prefilled.
With its flexibility and variable length depending on the force applied the
compression spring ensures completion of the injection before the needle cap
moves over the needle and subsequently the needle tip. In an embodiment
permanent securing of the needle and thereby the user's safety is achieved by
locking the barrel at the end of the barrel's movement which may be obtained
by
outward protrusions, e.g. in the form of barbs, of the barrel in cooperation
with a
backstop on the cylinder. In a preferred embodiment, the outward protrusions
of
the barrel are slanted and form a wedge-shaped profile in which the height of
the
protrusions increase in the direction against the closed end of the needle cap
and
are wedged in between the outer wall of the barrel and edge of the finger grip
in
order to create a backstop between the slanted outward protrusions
perpendicular surface and the perpendicular surface edge of the finger grip.
The
mechanical backstop opposite the emptying direction is achieved when the
slanted outward protrusions on their highest point have a height dimension
which
is greater than the recess but which due to the flexibility of the plastic
component
material and at the applied force are positioned through the opening which is
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created between the outer wall of the cylinder and the finger grip, and
eventually
wedged below and past the edge of the finger grip.
The use of a compression spring for starting movement of the piston and
the execution of the full injection also represent significant user related
advantages during the injection, since the initial movement of the piston
always
occurs at the same force application, irrespective of whether the spring is
compressed quickly or slowly which adverse handling often occurs because users
handle injection tools differently depending on physical differences between
individuals. According to the invention the piston will commence movement at
one particular application of force due to the force of the piston and
friction
relating to the surrounding cylinder inner wall, which will reduce undue
discomfort which is frequently experienced by patients receiving injections
and
instead give each injection identical smooth and comfortable characteristics
for
both user and patient.
In another embodiment the device for actuating the piston is a needle cap
having a tubular section with a fastening end comprising a device for
fastening,
e.g. releasably fastening, the needle cap to an inside wall of the barrel,
which
needle cap has a length, which is equal to or larger than an operating length
of
the cylinder defined by the distance from the actuating end of the cylinder to
the
outlet end of the cylinder minus the dimension of the piston parallel with the
longitudinal axis. The needle cap is thus located inside the barrel so that
when
the needle guard is mounted in the storage position from the outlet end, i.e.
with
the finger grip in the slot for receiving the finger grip, the needle cap
surrounds a
hypodermic needle attached to the outlet of the cylinder. In this embodiment
it is
preferred that a hypodermic needle is attached to the outlet of the cylinder.
It is
further preferred in this embodiment that the injector is prefilled.
The needle cap may be rigid or made from an elastomeric material. In a
specific embodiment the barrel is flexible in a transverse direction, and the
needle cap at the fastening end has a fastening device for engaging a
complementary fastening device on the inside wall of the barrel, which provide
a
device for releasably fastening the needle cap to the inside wall of the
barrel. The
barrel may have an oval transverse cross section, which provides flexibility.
In
this embodiment the smallest inner dimension is larger than, e.g.
approximately
equal to, the largest outer diameter of the cylinder leaving necessary room
for
expansion of the barrel. Thus, when the needle guard is mounted on the
cylinder
at the actuating end with the finger grip in the slot for receiving the finger
grip
the needle cap will push the piston towards the outlet end. When the barrel
has
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an oval transverse cross section the inner wall of the barrel may, at its
smallest
inner transverse dimension, comprise two inner opposite outward protrusions
interacting with the needle cap comprising a circular recess, each
representing
the respective fastening device and complementary fastening device. Upon
5 continued application of force to the needle guard the piston, having
reached the
outlet end of the cylinder, i.e. the post-injection position, will stop the
movement
of the needle cap and further force a transverse expansion of the smallest
dimension of the barrel so that the transverse flexibility of the barrel
releases the
fastening of the needle cap, which in turn allows the needle guard to be moved
to
10 its protective position.
In another aspect the invention relates to an injector comprising:
-a cylinder with a longitudinal axis and an inner wall and an outlet at an
outlet end of the cylinder opposite an actuating end of the cylinder,
-a piston having a piston body and a deformable sealing element, which
deformable sealing element abuts the inner wall of the cylinder at an abutting
interface and seals an annular gap between the piston body and the inner wall
of
the cylinder when the piston is inserted in the cylinder,
-a needle cap having a tubular section for actuating the piston, which
needle cap has a needle insertion end comprising an engagement device for
sealingly engaging a complementary engagement device of the outlet of the
cylinder when the needle cap is mounted on the cylinder, which needle cap has
a
length, which is equal to or larger than an operating length of the cylinder
defined by the distance from the actuating end of the cylinder to the outlet
end of
the cylinder minus the dimension of the piston parallel with the longitudinal
axis,
which tubular section consists of an elastomeric material. It is preferred
that the
injector comprises a hypodermic needle attached to the outlet of the cylinder.
Any variation of the needle cap used in this aspect may be employed as needle
cap in the first aspect of the invention.
The needle cap in this aspect can advantageously serve both as a cap for
sealing the contents of the injector, due to the elastomeric nature of the
tubular
section, and also serve as a piston rod for actuating the piston. Thus, the
elastomeric material will seal the hypodermic needle and prevent the contents
of
the syringe from leaking or evaporating. The elastomeric material will also
prevent contaminants from entering into the cylinder and thus prevent the
contamination of a pharmaceutical composition, e.g. a drug or a vaccine, in
the
cylinder. The piston may be solid so that its insertion in the cylinder is not
dependent on its orientation. This simplifies the manufacturing of the
injector
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ii.
compared to injectors having a piston rod engaging a piston with means for
receiving the piston rod. Furthermore, since the sealing effect is provided
from
the material of the needle cap no additional features are needed in order to
seal
the injector, making this aspect especially advantageous for prefilled
injectors. In
a preferred embodiment the injector is prefilled. The removal of the need of
additional features for sealing the injector emphasises the advantages
obtained
with a solid piston with respect to simplifying manufacture. However, in
another
embodiment the needle cap comprises a plug, which plug seals the hypodermic
needle when the engagement device is engaging the complementary engagement
device of the outlet of the cylinder.
Any elastomeric material may be used for the tubular section, but it is
preferred that the elastomeric material is a thermoplastic elastomer (TPE).
The
TPE may for example be a styrene block copolymer (SBC) selected from the list
consisting of hydrogenated SBC or non hydrogenated SBS or alloys of these. In
particular the tubular section may have a Shore A hardness in the range of 50
to
90, e.g. in the range of 70 to 90. A Shore A hardness in the range of 50 to 90
allows that the needle cap consists of the elastomeric material, since a
needle
cap with this Shore A hardness is sufficiently rigid despite the elastic
nature of
the material for the needle cap to be employed as a piston rod. In particular,
when a needle cap Shore A hardness in the range of 50 to 90 can be used to
actuate the piston without a collapse of the material, so that the injector
can be
emptied. The wall thickness of the tubular section will typically be in the
range of
0.5 mm to 5 mm. The needle cap can also comprise other materials, e.g. harder
plastic material such as ABS material, poly ethylene (PE), poly propylene (PP)
or
vulcanized rubber material or other material relevant for the purpose. The
needle
cap may for example combine a rigid outer material such as ABS, PE, or PP with
a softer inner material for embedding of the needle tip, said softer material
having a Shore hardness of between 29 and 80, such as Evoprene G966 or
Evoprene G967.
In an embodiment needle cap at a needle protection end opposite the
needle insertion end has a push-plate having a larger transverse dimension
than
a transverse dimension of the needle cap. The push plate may be disc shaped.
The push plate may further comprise an elastomeric material, e.g. the push
plate
may consist of an elastomeric material. The push plate may be used for
pushing,
e.g. with a finger, the piston towards the outlet end of the cylinder using
the
needle cap as a piston rod. The push-plate may have any size, e.g. with
respect
to the cross-sectional area, as deemed appropriate for the intended use.
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However, the push-plate typically has a larger cross-sectional area than the
cross-sectional area of the cylinder. For example, the push-plate may be round
and have a diameter of up to twice the inner diameter of the cylinder. The
presence of a push-plate increases the stability during administration of the
injection which is of great importance when exercising human injections.
Furthermore, the push plate increases user comfort when operating the syringe,
which is especially relevant during injections with larger syringes where the
force
needed to initiate movement of the piston (break loose force) is substantial
compared to smaller syringes. Consequently, the push plate area is typically
increased with increased cylinder diameter of which the latter is the
governing
parameter for the force needed to empty the cylinder. The push-plate may have
any shape but it will typically be a disc or an annular ring.
In a specific embodiment the engagement device comprises a lower
material thickness than the material thickness of the tubular section. For
example
the material thickness of the engagement device may in the range of 0.2 mm to
3.0 mm, e.g. 0.5 mm to 2.0 mm, depending on the cylinder nominal volume and
ultimately the size of the cylinder. A lower material thickness is especially
suited
for injectors having a glass cylinder where the outlet of the cylinder is
typically
produced with higher measurement values and tolerances than can be afforded
e.g. by injection moulding of thermoplastic materials. Therefore, the lower
material thickness at the engagement device allows the needle cap to be used
with injectors with glass cylinders. An injector with a glass cylinder will
typically
have a hypodermic needle attached to the outlet of the cylinder. The same
effect
can be obtained when the engagement device comprises perforations or an inner
cross-sectional area of the engagement device is larger than an inner cross-
sectional area of the tubular section. Thus, an engagement device comprising
perforations is likewise suited for use with an injector having a glass
cylinder, and
as is an engagement device having an inner cross-sectional area of the
engagement device larger than the inner cross-sectional area of the tubular
section.
In a particular embodiment the needle cap comprises a push plate and the
needle cap consists of the elastomeric material as defined above. This
embodiment is particularly suited for use in the first aspect of the invention
where the push plate of the needle cap forms the device for fastening, i.e.
releasably fastening, the needle cap to an inside wall of the barrel, which is
fitted
with protrusions for engaging the push plate. The elastomeric nature of the
push
plate provides that the needle cap is releasably fastened to a complementary
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fastening device on the inside wall of the barrel. Thereby the fastening will
be
released when moving the needle guard, i.e. using the needle guard with the
needle cap for actuating the piston, from the post-injection position to the
protective position. A push plate of an elastomeric material is particularly
suited
for any design of the needle cap as used a device for actuating the piston.
The second aspect of the invention enables manufacturers of syringe
cylinders to maintain their existing design and infra structure in production
and
instead of redesigning their cylinder in order to accommodate a needle cap
which
can be used as plunger or piston rod, the manufacturers can implement the
needle cap of the invention which is highly affordable compared to redesigning
the cylinder.
The material has an elasticity necessary to expand over a tubular outlet
and maintain this position during a shelf life of up to at least three years
and
when removed from its position is capable of contracting to at least a size
and
diameter enabling its insertion in the cylinder.
The needle cap may comprise a closed end which may be of a certain
thickness in order to embed the hypodermic needle in the needle cap material
when the needle cap is mounted on the outlet of the cylinder. The needle cap
has
a design and a flexible material capable of expanding and contracting around
an
interacting component such as a tubular outlet of a cylinder for an injector
containing a liquid medical substance, and where the 1st expansion and
contraction is achieved during mounting of the needle cap before use, and the
2nci
expansion and contraction is achieved when the needle cap is removed from its
position over the outlet of the syringe cylinder inserted into the cylinder to
function as a plunger.
In a further embodiment the needle cap comprises, at the tubular section
for actuating the piston, an air plug device, e.g. with respect to the
cylinder,
which air plug device forms an airtight barrier between the air plug device
and
the inner wall of the cylinder when the needle cap is inserted into the
cylinder.
The air plug device is preferably located at the end opposite the needle
insertion
end. Thus, when the needle cap having an air plug device is inserted into the
cylinder a volume of enclosed air will form in the cylinder between the
surface of
the piston and the air plug device, and when the needle cap is pushed towards
the outlet end of the cylinder the enclosed air will be compressed so that the
compressed air pushes the piston thereby ultimately moving the piston to the
outlet end for injection execution by emptying the cylinder. The needle cap
with
an air plug device thus enables a reduced length of the needle cap. When the
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needle cap comprises an air plug device the needle cap is not required to have
the length defined above but may be shorter. The needle cap, including the
length of the air plug device, and the length of the compressed air must
together
be equal to, or larger than, the operating length of the cylinder. For
example, the
needle cap with an air plug device may have a length of 70% to 95% of the
operating length. In general, this embodiment employs a clearance between the
actuating end of the cylinder and the actuating surface of the piston, of e.g.
5 mm to 20 mm, allowing formation of the volume of compressed air. This
embodiment is particularly relevant for injectors with cylinders with low
inner
diameters, and especially injectors of small volumes, e.g. about 1 ml or less.
For
example, the inner diameter of the cylinder may be 5 mm or less.
An injector having a needle cap with an air plug device is not limited to
having a needle cap with a tubular section consisting of an elastomeric
material
as defined above, and in a third aspect the invention relates to an injector
comprising:
-a cylinder with a longitudinal axis and an inner wall and an outlet at an
outlet end of the cylinder opposite an actuating end of the cylinder,
-a piston having a piston body and a deformable sealing element, which
deformable sealing element abuts the inner wall of the cylinder at an abutting
interface and seals an annular gap between the piston body and the inner wall
of
the cylinder when the piston is inserted into the cylinder,
-a needle cap having a tubular section for actuating the piston, which
needle cap has a needle insertion end comprising an engagement device for
engaging a complementary engagement device of the outlet of the cylinder when
the needle cap is mounted on the cylinder, which needle cap has a length,
which
is equal to or larger than an operating length of the cylinder defined by the
distance from the actuating end of the cylinder to the outlet end of the
cylinder
minus the dimension of the piston parallel with the longitudinal axis, which
needle cap at the tubular section for actuating the piston comprises an air
plug
device as defined above. The air plug device is preferably at the end opposite
the
needle insertion end. The material of the needle cap in this aspect may be
chosen
freely, and in a specific embodiment it is injection moulded from a
thermoplastic
polymer. However, all variations and embodiments of the needle cap described
for the second aspect of the invention are also relevant for this aspect of
the
invention.
In either aspect of the injector the piston may be injection moulded from a
TPE, in particular having a Shore A hardness in the range of 50 to 90. A
piston
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having a Shore A hardness in the range of 50 to 90 allows that the piston is
used
without lubrication. In another embodiment the injector does not comprise a
lubricant.
The injector may comprise, e.g. at the outlet end, a fitting for attaching or
5 mounting a hypodermic needle. The cylinder may thus have a tapered
outlet, e.g.
a tubular outlet, from the cylinder providing an engagement device for
engaging
a complementary engagement device of a hypodermic needle, e.g. the
engagement device and the complementary engagement device may comprise a
male-female interaction, with the tubular outlet optionally comprising an
external
10 thread, e.g. a helical external thread, and the hypodermic needle
optionally
comprising a complementary internal thread, e.g. a helical internal thread. A
hypodermic needle may be fitted to allow simple removal, and replacement, of
the hypodermic needle, or the hypodermic needle may be mounted permanently
on the injector. In particular, the hypodermic needle may be mounted on the
15 injector so that its removal requires the destruction of the injector
thereby
preventing reuse, which in the context of the invention is considered
"permanent".
In an embodiment of the invention the injector, preferably prefilled, is a
syringe with a hypodermic needle. The syringe may have a hypodermic needle
mounted, e.g. permanently mounted, on a tubular outlet or an outlet of another
shape. When the injector is prefilled, in particular when it also comprises a
needle
cap for use as a piston rod, there may be a clearance between the actuating
end
of the cylinder and the actuating surface of the piston. The clearance ensures
stability of a piston rod when this is inserted in the cylinder, which results
in a
safer and easier operation of the injector. The clearance, e.g. measured in
units
of length, may be any value relevant for the size, e.g. volume, of injector
and the
dose of pharmaceutical composition in the injector. Typical values for the
clearance are between about 2 mm to about 20 mm.
In an embodiment the piston has two or more deformable sealing
elements, and the piston is solid, i.e. it does not have a cavity or the like.
A solid
piston having two or more deformable sealing elements may be symmetrical
relative to a transverse plane so that its orientation when inserted in the
cylinder
is not relevant. In contrast, an asymmetrical piston, e.g. a piston having a
cavity,
such as a cavity for housing a piston rod, needs to be oriented prior to
insertion
into the cylinder, e.g. so that the piston may be actuated by the needle cap
inserted in the cavity. The removal of the need to orient the piston greatly
simplifies production of syringes, e.g. prefilled syringes, and thereby
reduces the
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production costs. It is preferred that the solid piston does not comprise any
means to engage a piston rod or plunger. Similarly the replacement of a
traditional needle cap by the needle cap of the invention reduces the
production
costs by eliminating a traditional plunger connected to the piston.
The piston comprises a deformable sealing element. In the context of the
invention, the term "deformable" describes that the deformable sealing element
may be deformed and thereby seal an annular gap between the piston and the
inner wall of the cylinder. The deformable sealing element will thus have
dimensions in a relaxed state, e.g. in a state without deformation, such as
deformation caused by inserting the piston in a cylinder, and the diameter,
e.g.
of the piston including the deformable sealing element, in the relaxed state
will
be larger than the inner diameter of the cylinder of the injector. This
ensures that
the deformable sealing element will seal the annular gap between the piston
and
the inner wall of the cylinder. The diameter of the deformable sealing element
is
typically 3% to 20% larger than the inner diameter of the cylinder, e.g. 5% to
15% larger.
At the location where the deformable sealing element abuts the inner wall
of the cylinder the interface between the deformable sealing element and the
inner wall will provide a static friction and a dynamic friction. Movement of
the
piston in the cylinder will require application of a force sufficient to
overcome
initially the static friction and subsequently the dynamic friction; the
static friction
will be larger than the dynamic friction and thereby the force to provide an
initial
movement of the piston is larger than the force required to provide a
sustained
movement of the piston. Once the piston has stopped moving the force to
provide an initial movement must be overcome again. In general, the inner wall
of the cylinder requires lubrication in order to keep the dynamic friction
sufficiently low to ensure sufficient glide for the piston and allow for easy
movement of the piston in the cylinder and thereby easy delivery of a
pharmaceutical composition during injection. In a specific embodiment the
injector, e.g. the piston, does not comprise a lubricant; in particular when
the
deformable sealing element has a Shore A hardness in the range of 50 to 90,
e.g.
70 to 80, no lubricant is needed.
The piston may be made from any material. In particular, the piston body
is not in contact with the inner wall of the cylinder and the material of the
piston
body is generally only required to be inert with respect to any pharmaceutical
composition in the injector. The deformable sealing element should likewise be
inert with respect to the pharmaceutical composition in the injector. In a
certain
17
embodiment of the invention the piston and the deformable sealing element are
of the same material, e.g. the piston body and the deformable sealing element
are of the same material. By providing the piston, e.g. the piston body, and
the
deformable sealing element, and any optional supporting sealing elements, from
the same material, a more cost-effective and simple production is made
possible,
thereby to a large extend avoiding different process steps e.g. time-consuming
assembly.
The deformable sealing element is made from a material of an appropriate
hardness and elasticity to ensure that the annular gap between the piston and
the inner wall of the cylinder is sealed. Any such material may be chosen for
the
deformable sealing element. In a preferred embodiment the piston of the
invention is made by injection moulding from an appropriate TPE. Any TPE may
be used. Appropriate thermoplastic polymers comprise styrene block copolymers
(SBCs), e.g. hydrogenated - H-SBC - (SEBS - styreneethylene butylenes-styrene
or similar) or non hydrogenated (SBS - styrene-butadienestyrene) or alloys of
these and other compatible polymers. Preferred SBCs are those known under the
trademark Evoprene as marketed by AlphaGary Corporation (Leominster, MA,
USA). Evoprenes are described in the brochure "EVOPRENETM Thermoplastic
Elastomer (TPE) Compounds - GENERAL INFORMATION" (published by
AlphaGary, July 2007), and preferred EvopreneTM polymers are EvopreneTM Super
G, Evoprenerm G, EvopreneTM GC, and EvopreneTM HP, which are described in the
brochures "EVOPRENETM SUPER G Thermoplastic Elastomer (TPE) Compounds",
"EVOPRENETM G Thermoplastic Elastomer (TPE) Compounds", "EVOPRENETM GC
Thermoplastic Elastomer (TPE) Compounds", and EVOPRENETM HP Thermoplastic
Elastomer (TPE) Compounds (published by AlphaGary, July 2007), respectively.
When the piston is injection moulded the piston can be made with lower
tolerances that afforded by technologies such as vulcanisation, which is
commonly used in the manufacture of traditional rubber pistons. Appropriate
materials comprise elastomers, such as rubbers, e.g. natural rubber, synthetic
rubber (polyisoprene rubber, butyl rubber), silicone rubber, and the like,
which
may be defined with respect to e.g. the Shore durometer, which indicates the
elasticity of the elastomeric material and measures the hardness of the
elastomeric material, where the higher the durometer, the harder the compound.
For example, in an embodiment of the invention the deformable sealing element
has or the piston and the deformable sealing element have a Shore A hardness
in
the range of about 50 to about 90, preferably 60 to 80, more preferred 71 to
76.
Date Regue/Date Received 2022-12-12
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The
terms "Shore hardness" and "Shore d u ro meter" may be used
interchangeably. In general, the deformable sealing element will be
homogeneous and composed of the same material throughout the volume of the
deformable sealing element, which material has a Shore A hardness in the given
ranges. By using a material with a Shore A hardness in the above mentioned
range, a relatively hard elastomeric material is provided. It should be noted
that
Shore A durometer is only one of many ways to characterise the material
properties of the chosen material, and that other tests may also be employed
to
characterise the material.
The surface of the deformable sealing element may have any shape
desired. In a certain embodiment the deformable sealing element has a convex
surface, although the surface is not limited to convex shapes. In this context
the
term "convex" means that a straight line between any two points within the
deformable sealing element does not cross the surface of the deformable
sealing
element.
The cylinder and/or the barrel may each be one single component
preferably made from injection moulded plastic material known as COC or COP
with characteristics similar to glass and with excellent barrier
characteristics
although it can be made of other plastic material or glass or any other
material
relevant for the purpose. The barrel design is unusual since the finger grips
are
positioned downstream of the barrel towards the needle, which is necessary for
optimum interaction with the needle guard during safeguarding of the needle.
The interaction of the barrel with the needle guard for safeguarding of the
needle
is achieved through the interaction between the needle guard's slots and the
barrel's finger grips whereas the slots allow for the necessary travel
distance of
the needle guard in order to pass and ultimately safeguard the needle. The
relationship between the slots and the position of the finger grip(s) is
unusual
compared to regular syringes with incorporated means of needle stick
protection,
due to the absence of slots and traditional position of the barrel's finger
grips by
the open end of the barrel. The position of the finger grip of the barrel is
calculated with respect to the length and width of the slot in such a way that
the
finger grips are not positioned further away from the needle than the length
between finger grip upper edge and needle tip plus the addition of a
comfortable
safety margin to ensure full and sufficient safeguarding of the needle. The
barrel
may further be equipped with guide vanes in the area of the barrels open end
ensuring correct horizontal mounting of the needle guard before injection
leading
to correct interaction between the slots and the finger grips.
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The invention may function in the following way. Prior to injection the
needle guard may be mechanically linked to the needle cap via the interaction
between inner outward protrusions of the barrel and the e.g. circular
activating
end of the device for actuating the piston which two interacting components
are
dismantled from their needle protective and sealing position at the barrel's
needle
end and mounted in the barrel with the needle cap's open end first according
to
the barrel's orientation guide vanes ensuring the correct positioning of the
slots
of the needle guard with respect to passing the barrel's finger grips, where
after
the injection is executed by activation of the needle guard's operating end
towards the needle by which the needle cap's open end abuts and forces the
piston downward through the cylinder until the piston reaches and stops at the
time of completed injection. After withdrawing the injector from the injection
area
and without change of finger grip or hand attitude safeguarding of the needle
is
obtained by continued application of force via downward activation of the
needle
guard which forces the barrel past the tip of the hypodermic needle attached
to
the outlet of the cylinder, e.g. by forcing lower outward protrusions' slanted
surfaces against the upper surface of the barrel causing a sideways movement
of
the needle guard which may expands due to an oval shape allowing for further
expansion due to the flexible oval expanding perpendicularly and over its
shortest
diameter and allowing the protrusions departure from their surrounding of the
needle cap's fastening end to continue their motion towards passing and
enclosing the tip of the hypodermic needle, which is achieved with a minimum
safety margin preventing inadvertent contact with the hypodermic needle at the
same time as the lower outward protrusions of the cylinder pass and interlock
against the barrel's inward protrusions establishing a strong mechanical back
stop and ultimately a safeguarding of the hypodermic needle.
In an embodiment the barrel of the needle guard is flexible in its
transverse direction in order to achieve firstly the outward protrusions'
departure
from surrounding of the circular fastening end of the needle cap and secondly
in
order to achieve the outward protrusions' passing of and interlocking against
the
barrel's inward protrusions, which flexibility can be achieved either by
choosing a
flexible material or achieved as described in the preferred embodiment of the
invention where the barrel is oval-shaped allowing the temporary expansion of
the needle guard at its smallest diameter. The combination of material and
shape
decides which final shape barrel of the needle guard will have according to
the
wanted functionality. Although the preferred needle guard embodiment has an
oval-shaped barrel the barrel can be circular, square shaped or have any shape
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as long as the material is flexible enough to accommodate the necessary
expansion needed. The inner protrusions of the barrel may be rectangular,
circular, quadratic or square shaped although a triangular shape has been
chosen
to illustrate the lower outward protrusions in needle guards longitudinal axis
with
5 the hypotenuse pointing down and inward and the upper outward protrusions
being parallel to the opposite slanted surface of the barrel's inward
protrusion
with which the needle guard's outward protrusion interacts during interlocking
between the needle guard and the barrel.
The area between the upper and lower protrusion of the needle guard may
10 be round, square, rectangular or have any shape suitable for mechanical
interaction with the needle cap's activating end's shape. The needle cap's
fastening end interacting can be with right angles to its vertical plane, it
can be
square, rounded or any shape as long as it can mechanically interact with the
area between the needle guard's upper and lower protrusions. In an alternative
15 embodiment of the invention the needle guard comprises two oppositely
positioned protrusions for mechanical interaction with a circular recess, e.g.
a
push plate, of a needle cap's fastening end which recess accommodates the
protrusions. The needle cap's recess can be circular, quadratic, rectangular,
or
square shaped. Similarly the areas surrounding the recess may have rounded or
20 angled characteristics.
The barrel's outward protrusions may be circular, quadratic, rectangular,
or square shaped although a triangular.
Brief description of the figures
In the following the invention will be explained in greater detail with the
aid of an example and with reference to the schematic drawings, in which
Figure 1 shows an embodiment of an injector for preventing accidental
needle sticks of the invention in a storage position;
Figure 2 shows a top view of an injector for preventing accidental needle
sticks of the invention;
Figure 3 shows a side view of an injector for preventing accidental needle
sticks of the invention in a storage position;
Figure 4 shows an injector for preventing accidental needle sticks of the
invention in a protective position;
Figure 5 shows a side view an injector for preventing accidental needle
sticks of the invention in a protective position;
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Figure 6 shows an injector for preventing accidental needle sticks of the
invention having a compression spring in a storage position;
Figure 7 shows an injector for preventing accidental needle sticks of the
invention having a compression spring;
Figure 8 shows an injector for preventing accidental needle sticks of the
invention having a compression spring in a post-injection position;
Figure 9 shows an injector for preventing accidental needle sticks of the
invention having a compression spring in a protective position;
Figure 10 shows an injector for preventing accidental needle sticks of the
invention having a needle cap in a storage position;
Figure 11 shows an injector for preventing accidental needle sticks of the
invention having a needle cap;
Figure 12 shows an injector for preventing accidental needle sticks of the
invention with a needle cap in its protective position;
Figure 13 shows an injector for preventing accidental needle sticks of the
invention having a needle cap in a storage position;
Figure 14 shows an injector for preventing accidental needle sticks of the
invention having a needle cap;
Figure 15 shows an injector for preventing accidental needle sticks of the
invention having a needle cap in a post-injection position;
Figure 16 shows an injector for preventing accidental needle sticks of the
invention having a needle cap in its protective position;
Figure 17 shows a top view of an embodiment of an injector for preventing
accidental needle sticks of the invention;
Figure 18 shows an embodiment of an injector of the invention;
Figure 19 shows an embodiment of an injector of the invention;
Figure 20 shows an embodiment of an injector of the invention;
Figure 21 shows an embodiment of an injector of the invention;
Figure 22 shows an embodiment of an injector of the invention with an air
plug device.
Detailed description of the invention
The present invention relates to injector for preventing accidental needle
sticks and to an injector. The present invention will now be described in
greater
detail with reference to the appended drawings. The figures are generally
depicted as "cross-sectional views" of the injectors of the invention, where
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certain figures present side views where the injector in the "cross-sectional
view"
is depicted at an angle of 900 compared to the injector otherwise depicted.
Figure 1 shows an injector 10 for preventing accidental needle sticks. The
injector 10 comprises a cylinder 2 extending along a longitudinal axis, an
inner
wall and an outer wall, the cylinder having an outlet 3 at an outlet end 21
opposite an actuating end 22 and a finger grip 4 on the outer wall, which
finger
grip is positioned between the outlet end 21 and the actuating end 22. The
injector has a piston, which is not shown in Figure 1. A top view of the
injector is
shown in Figure 2. The injector comprises a needle guard 5 for mounting on the
outside of the cylinder 2 from the outlet end 21 (as shown in Figure 1) or the
actuating end 22 (as shown in Figure 4 and Figure 5), which needle guard 5
comprises a barrel 51 with a mounting end 52 opposite an operating end 53, the
barrel 51 having a slot 54, which is not visible in Figure 1, but which can be
seen
in the side view shown in Figure 3, for receiving the finger grip 4 of the
cylinder 2
when the needle guard 5 is mounted on the cylinder 2, which slot extends from
the mounting 52 end towards the operating end 53. The slot 54 is likewise
shown
in the side views in Figure 5 and in the right panel of Figure 13. When the
needle
guard 5 is mounted on the cylinder from the actuating end 22 in a protective
position, the barrel 51 extends along the longitudinal axis and projects
beyond
the outlet end 21 of the cylinder 2 so that when a hypodermic needle 24 is
attached at the outlet end 21, the barrel 5 protects a user from accidental
needle
sticks (Figure 4, Figure 5). The injector 10 may comprise a hypodermic needle
24, e.g. attached in a way so that its removal requires destruction of the
injector,
i.e. permanently attached, or the hypodermic needle 24 may be attached in a
way allowing removal. In an embodiment the injector 10 does not comprise a
hypodermic needle 24 but is designed to be used with standard hypodermic
needles of the field.
The cylinder 2 may comprise guide vanes (not shown) at the actuating
end 22 of the cylinder for ensuring correct horizontal mounting of the needle
guard 5 and showing the finger grip 4 for interaction with the slot 54. The
cylinder 2 may further comprise vertical stability fins (not shown) for stable
injection and mounting of needle guard before dismantling.
The cylinder 2 may have an outside diameter creating an inward
protrusion (not shown), e.g. as a rectangular outward protrusion or a circular
protrusion for interaction with outward protrusions of the barrel. The
cylinder 2
may have backstop(s) as an outward protrusion of a triangular shape.
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23
The needle guard 5 may be provided with a device for actuating the piston
23, which can move the piston from the actuating end towards the outlet end of
the cylinder when the needle guard 5 is mounted on the cylinder 2 from the
actuating end 22. Figure 6 shows an embodiment where the device for actuating
the piston 23 is a compression spring 41. The compression spring 41 is
attached
at the operating end 53 of the needle guard 5, and when the needle guard is
mounted in the storage position, as shown in Figure 6, the compression spring
41
may be slightly compressed. The barrel 51 and the cylinder 2 may be provided
with appropriate devices, e.g. barbs or the like (not shown) for retaining the
needle guard 5 in the storage position. When the needle guard 5 is removed
from
the outlet end 21 the compression spring will extend to its relaxed state
since no
extending force is applied. The the needle guard 5 is mounted on the actuating
end 22 of the cylinder 2 and the needle guard 5 is pushed toward the outlet
end
21 of the cylinder 2, and the compression spring 41 will contact the piston 23
and
push the piston 23 toward the outlet end 21 thereby emptying the cylinder 2.
The
procedure is illustrated in Figure 7, Figure 8 and Figure 9. In Figure 8 the
needle
guard 5 is shown in its post-injection position. In Figure 9 the needle guard
5 is
shown in its protective position.
In another embodiment, shown in Figure 10 to Figure 12, the injector 2
has a needle guard 5 with a device for actuating the piston in the form of a
needle cap 42. The needle cap 42 is fastened at the actuating end 53 of the
needle guard 5.
In another embodiment, shown in Figure 13 to Figure 16, the device for
actuating the piston is a needle cap 42 having a tubular section 401 with a
fastening end comprising a device 431 in the form of a push plate, e.g. of an
thermoplastic elastomer (TPE), for fastening the needle cap to an inside wall
of
the barrel 51 at a complementary fastening device 432, which needle cap 42 has
a length, which is equal to or larger than an operating length of the cylinder
2
defined by the distance from the actuating end 22 of the cylinder 2 to the
outlet
end 21 of the cylinder 2 minus the dimension of the piston 23 parallel with
the
longitudinal axis. It is to be understood that when the barrel 51 has an oval
transverse cross section the complementary fastening device 432 (presented
with
dotted lines in the left panel of Figure 13) is located at or close to points
on the
narrow axis which allows that it together with the device 431 for fastening
the
needle cap form a flexible, and thereby releasable, fastening. In the left
panel of
Figure 13 the barrel 51 is shown at a right angle to the barrel 51 in the
right
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24
panel where the slot 54 is visible together with the complementary fastening
device 432.
In a specific embodiment the barrel 51 is flexible in a transverse direction,
and the needle cap 42 at the fastening end has a fastening device 431 for
engaging a complementary fastening device 432 on the inside wall of the barrel
51, which provide the device for fastening the needle cap to the inside wall
of the
barrel 51, wherein the fastening is releasable. The barrel Si. may have an
oval
transverse cross section as shown in Figure 17 where the oval cross-section
and
the material of the barrel 51 allow that the smallest dimension of the cross-
section is pushed outward to release the fastening. In another embodiment the
needle cap 42 has a push-plate of a flexible material, e.g. a TPE or another
type
of elastomer, thereby providing a releasable fastening between the fastening
device 431, the push-plate, and the complementary fastening device 432 (see
Figure 15 and Figure 16).
Figure 13 shows the needle guard 5 in its storage position, Figure 15
shows the needle guard 5 in its post-injection position, and Figure 16 shows
the
needle guard 5 in its protective position.
Figure 18 and Figure 19 show the second aspect of the invention. Thus,
Figure 18 and Figure 19 show an injector 100 comprising a cylinder 2 with a
longitudinal axis and an inner wall and an outlet 3 at an outlet end 21 of the
cylinder 2 opposite an actuating end 22 of the cylinder 2. The injector has a
piston 23 having a piston body and a deformable sealing element, which
deformable sealing element abuts the inner wall of the cylinder at an abutting
interface and seals an annular gap between the piston body and the inner wall
of
the cylinder 2 when the piston 23 is inserted in the cylinder 2. The injector
has a
needle cap 400 having a tubular section 401 for actuating the piston 23, which
needle cap 400 has a needle insertion end 402 comprising an engagement device
for sealingly engaging a complementary engagement device of the outlet 3 of
the
cylinder 2 when the needle cap 400 is mounted on the cylinder 2, which needle
cap 400 has a length 409, which is equal to or larger than an operating length
405 of the cylinder defined by the distance from the actuating end 22 of the
cylinder to the outlet end 21 of the cylinder 2 minus the dimension 406 of the
piston parallel with the longitudinal axis, which tubular section 401 consists
of an
elastomeric material. The elastomeric material may a be a TPE, such as a
styrene
block copolymer (SBC) selected from the list consisting of hydrogenated SBC or
non hydrogenated SBS or alloys of these. In a specific embodiment the tubular
section 401 has a Shore A hardness in the range of 50 to 90.
CA 02988168 2017-12-04
WO 2016/192739 PCT/DK2016/050164
The needle cap 400 at a needle protection end 407 opposite the needle
insertion end 402 has a push-plate 408 having a larger transverse dimension
than a transverse dimension of the needle cap 400. The push plate 408 may be
disc shaped, and it may comprise an elastomeric material, e.g. a TPE.
5 The needle cap 400 may comprise a plug 410, which seals the
hypodermic
needle 24 when the engagement device is engaging the complementary
engagement device of the outlet 3 of the cylinder 2. The plug 410 thus adds a
further fail-safe mechanism for sealing the contents of the cylinder 2.
In the embodiment shown in Figure 20 the needle cap 400 the
10 engagement device 403 comprises a lower material thickness than the
material
thickness of the tubular section 401. The left panel of Figure 20 shows the
needle
cap 400 before mounting on the outlet 3, and the right panel shows the needle
cap 400 mounted on the outlet 3. This embodiment is particularly suited for an
injector 100 having a glass cylinder 2, where the outlet 3 is typically
bigger, due
15 to higher tolerances of manufacturing glass syringes, than for a
cylinder of an
injection moulded thermoplastic polymer. The material thickness of the
engagement device 403 may for example be in the range of 0.2 mm to 1.0 mm.
The lower material thickness allows easier mounting of the needle cap 400 on
the
outlet 3 of the cylinder 2. The same effect can be obtained when the
engagement
20 device 403 comprises perforations (not shown). The embodiment in
Figure 20
has a piston 23 with a hollow section for housing, and optionally engaging, a
piston rod (not shown).
A further embodiment suited for an injector 100 having a glass cylinder 2
is shown in Figure 21, where an inner cross-sectional area of the engagement
25 device 403 is larger than an inner cross-sectional area of the
tubular section 401.
This needle cap 400 of this embodiment can likewise be more easily mounted on
the outlet 3 of a glass cylinder 2.
Figure 22 shows an embodiment of the injector where the tubular section
401 of the needle cap 400 an air plug device 411. In the left panel the needle
cap
400 is mounted on the outlet 3 of the cylinder 2, and in the right panel the
needle cap has been inserted into the cylinder 2 and the piston 23 has been
pushed to the outlet end of the cylinder 2 by the compressed air 412 formed by
the air plug device 411.
